How much does a 5.00ct+ I SI2 natural marquise diamond cost?

As of September 2026, 5.00ct+ I SI2 natural marquise diamonds typically cost $63,564 AUD to $229,991 AUD, with a median price of $130,750 AUD. There are currently 24 diamonds matching this specification available across retailers.

Where can I find the best price on a I SI2 marquise diamond?

Compare prices across retailers on Carat Hunter to see all your options.

5.00ct+ I SI2 Natural Marquise

Quick answer

As of September 2026, there are 24 natural marquise diamonds with I colour and SI2 clarity in the 5.00ct+ range available across retailers worldwide. Prices typically run $63,564 AUD to $229,991 AUD, with a median of $130,750 AUD. At least 4 retailers stock this exact specification. Half of all listings fall between $29,638 AUD and $38,613 AUD per carat.

Three of the best scored stones at this specification right now:

Caratlytics Diamond Price Index, August 2026: natural diamonds at 2,184 USD per carat and lab-grown at 464 USD per carat, a natural to lab ratio of 4.7 to 1. Marquise natural stones in the index: 2,114 USD per carat, -8.8% month on month. See the full index release

Figures come from live listings across more than 100 retailers and refresh daily. The index is a monthly release.

Last updated: September 2026

Available

Lowest Price

$56,415 AUD

Highest Price

$379,363 AUD

Average Price

$143,663 AUD

Market Intelligence

Retailers Selling

Price Spread

25.0%

Price Range

Price per carat distribution across retailers

$23,365/ct

10th Percentile

$16,384

Median

$23,365

90th Percentile

$28,647

Score Distribution

24 diamonds scored across 4 quality tiers

Excellent

2 (8.3%)

Very Good

9 (37.5%)

Good

5 (20.8%)

Average

8 (33.3%)

Find Your Diamond

Search 24 I SI2 marquise diamonds and compare prices.

Search Diamonds

Consider Instead

Save money without compromising on what matters. These alternatives are visually similar but cost less.

J SI2J colour is visually identical to I to the naked eye

Save 52%

I I1I1 inclusions are not visible without magnification

Save 67%

Related Specifications

D IF D VVS1 D VVS2 D VS1 D VS2 D SI1 E IF E VVS1 E VVS2 E VS1 E VS2 E SI1 F IF F VVS1 F VVS2 F VS1 F VS2 F SI1 G IF G VVS1 G VVS2 G VS1 G VS2 G SI1 H IF H VVS1 H VVS2 H VS1 H VS2 H SI1 I IF I VVS1 I VVS2 I VS1 I VS2 I SI1